Tankship container for liquefied gas

ABSTRACT

1,138,127. Ships&#39; fittings &amp;c. LINDE A.G. 30 Aug., 1967 [1 Sept., 1966], No. 39559/67. Heading B7S. [Also in Division F4] The thin flat metal walls of a generally rectangular liquefied gas storage container are spaced by a supporting layer of heat-insulation material 11, Fig. 2, from the inner plating 10 of a ship&#39;s hull and the marginal edges of each wall 1 are rigidly secured by screw bolts 7 to said inner plating 10 and the metal of which the container is made, e.g. aluminium, is such that on initial cooling the walls are plastically deformed resulting in permanent folds being formed when the container is rewarmed. The bolts 7 pass through relatively thick profiled aluminium sections 2 which are welded along thin margins 3, Fig. 1, to adjacent wall plates 1. In each corner of the container the margin sections 3 are welded to edge extensions 5 of a cube-shaped element 4 through which bolts 8 pass to the inner plating 10. An inner liquidholding shell 13 is spaced by resilient insulation 12, e.g. slag wool, from the walls 1 and has spaced feet 14 only one of which is shown resting on insulation blocks 15, 16 between which the bottom wall 1 passes. A shear rail 23 fixed to the bottom of the inner shell 13 is anchored in a groove formed by metal strips 17 welded to the bottom of the hull and insulation blocks 20, 21. A rigid channel-section 21 of the bottom wall 1 is also anchored in the grooves.

Dec. 23, 1969 R. BECKER 'TANKSHIP CONTAINER FOR LIQUEFIEDGAS 2 Sheets-Sheet l Filed April 28, 1967 Dec. 23, 1969 R. BECKER TANKSHIP CONTAINER FOR LIQUEFIED GAS Filed April v28, 1967 2 Sheets-Sheet 2 Rudolf Becker I N VENTOR.

Attorney United States Patent O 3,485,409 TANKSHIP CONTAINER FOR LIQUEFIED GAS Rudolf Becker, Munich, Germany, assignor to Linde Aktiengesellschaft Zentrale Patentabteilung, Hollrlegelskreuth, Germany, a corporation Filed Aug. 28, 1967, Ser. No. 663,577 Claims priority, application Grmany, Sept. 1, 1966,

Inf. c1. Bsd 25/14 U.S. Cl. 220-9 12 Claims ABSTRACT OF THE DISCLOSURE My present invention relates to tankships for the transportation of liquefied gas and, more particularly, to improvements in receptacle constructions for such tankships.

In U.S. Patent No. 3,314,567, I, together with another, have disclosed and claimed a receptacle construction for use in tankships designed for the transportation of liquefied gases. Liquefed gases, as referred to hereinafter, are generally characterized as liquids which are gases at ambient temperature and are stored and transported in the condensed state, sometimes under pressure but more generally at a temperature well below the boiling point of the liquefied gas. Consequently, tankships for the transportation of such fiuids may be provided with heat-exchange apparatus, refrigeration equipment and the like. For maintaining the fluid in a liquid state and with insulated receptacles for the fluid designed so that, even during prolonged periods of transport, the liquid is not heated above its boiling point. The more commonly used liquefied gases are the hydrocarbons having a boiling point at or somewhat below ambient temperature (eg. methane, ethane and propane), ammonia and the like. As pointed out in the aforementioned patent, several significant considerations enter into the design of tankships for the transportation of liquefied gases and the receptacles used therein. On the one hand, the tanks must be mounted in the hold of the ship so as to be thermally insulated from the hull and yet must be firmly secured therein to eliminate undue stress upon the receptacle walls and the mounting assemblies arising from the motions of the ship during sea travel in stormy or calm waters. Furthermore, variations in temperature during loading of the receptacle, unloading of the receptacles and transportation of the gas causes expansion and contraction which create stresses not only in the wall structure but also at the means connecting the receptacles to the hull of the ship. These ther mal expansion-and-contraction movements have a tendency to produce material fatigue which may be pronounced at the low temperatures at which the liquefied gas is stored. In the patented system discussed above, the liquefied-gas receptacles are provided with walls of a generally corrugated construction formed by welding together cylindrical shell segments along generatrices of the segments. In this manner, each vertical wall-type buildup of a plurality of such shell sections while the edgesare formed with 90 sections, the corners form quarter spheres of similar diameter, etc. The output stresses upon the walls are taken up by tension members spanning the ice containers and welded to the walls at the seams between the cylindrical sections. Generally, double-wall vessels are provided with thermal insulation between the outer wall and the hull of the ship and between the shells forming the walls. In addition, thernounting assemblies for retaining the receptacles in the ships hull are designed to permit movement of the walls generally parallel to themselves for thermal expansion and contraction to prevent shear stresses on the mounting means and for compensating the thermal distortion of the receptacle walls. In some cases, such structures are relatively expensive because they involve multiple welded seams which must be tested and which may fail under stress.

It is therefore, the principal object of the present invention to provide an improved container structure for the transportation of liquefied gases in tankships and the like. Another object of my invention is to provide an improved method of making a receptacle of this character.

Still a further object of the instant invention resides in the provision of a receptacle for the low-temperature storage of liquids which are gaseous at ambient temperatures, the receptacles being characterized by a minimum number of weld seams, by high structural strength, by the capacity to compensate for thermal changes in dimension and by particularly convenient configuration whereby the container may be mounted in the hold of a seagoing vessel.

I have now found, surprisingly, in view of the previously believed qualities of sheet aluminum, that when an aluminum sheet or plate is retained in a support frame and subjected to low temperatures, there is no significant embrittlement of the sheet and no shrinkage-type rupture, but a tendency for the sheet to become plastically deformable (apparently because of some intercrystalline fiow of metal) whereby shrinkage occurs without breakage; upon heating, the normal expansion of the aluminum plate distorts it relatively uniformly to form multiple ridges and troughs extending substantially uniformly across the entire sheet and forming in effect bellows-like corrugations or wrinkles which, when the aluminum plate is constituted as a wall of the container for storing liquefied gas, enables thermal expansion and contraction while avoiding the need for multiple seams, pre-formation of cylindrical sections, etc.

Accordingly, it is a principal feature of the present invention to provide a method of making a container for receiving liquefied gases which comprises the steps of mounting a plurality of planar aluminum sheets in respectlve, generally rectangular frames, assembling the frames into a prismatic receptacle structure and sealing the structure against escape of fiuid therefrom, cooling the walls of the structure to temperatures of C. and below to effect a plastic deformation shrinkage of the plates spanning the frames, thereafter raising the temperature of the walls to effect corrugation thereof, and introducing liquefied gas to be transported into the receptacle thus formed. The cooling of the receptacle is preferably carried out by treating the walls with a liquefied gas or freshly vaporized liquefied gases.

According to another aspect of this invention, the receptacle is constituted of fiat sheets of aluminum so assembled that their edges and corners are in force-transmitting relationship with the walls, edges: and corners of the ships hull and are secured thereto via a layer of load-supporting thermal insulation, The edges and corners are maintained at their original spaced relationship by the steel plates of the ships hull so that the initial plastic deformation of the plates is effected by thermally tensioning the plates in a frame formed by the edge and comer members and the hull walls. It is within this frame that the subsequent expansion of the sheet-aluminum plates is effected to produce the corrugations.

According to a further feature of this invention, the

composed of relatively rigid profiles of the same metal, i.e. extruded aluminum bars which, when bolted or otherwise joined to the hull of the ship, undergo minimum deformation with temperature variations except in the planes of the respective frames, the profiles having marginal portions or laps welded to the aluminum sheets and forming transition members which converge from the thickness of the aluminum profile to the thickness of the sheet. These relatively rigid profiles are, according to this invention, secured to the inner wall of the ships hull by bolt assemblies of low thermal conductivity while a layer of load-supporting thermal insulation is disposed between the receptacle shell and the wall of the hull. The loadsupporting thermal insulation is advantageously a fabricreinforced synthetic resin f the type marketed under the name Ferrocell (Ferrozel). When the receptacle wall of thermally wrinkled aluminum sheet, prepared in the manner described above, forms a liquid-type vessel, the heads of the bolts within the shell are welded in a liquid-tight manner to the inner wall surfaces.

According to still another specific feature of this invention, the edge profile bars at the corner of a rectangular or trapezoidally prismatic vessel are reinforced by generally cubic corner bodies secured by bolt assemblies of low thermal conductivity in three mutually perpendicular and spaced directions to the ships hull in force-transmitting fashion. Furthermore, it is advantageous to provide, in some cases, between the sheet metal aluminum plates deformed to have wrinkles, corrugations or folds by warming subsequently to a deep-cooling, with spacer studs or pins bridging the space between these plates and the ships hull, the pins being affixed to the plates and the hull and affording limited movement of the receptacle walls parallel to the plane of the plate.

Still another aspect of this invention resides in the provision of the vessel as a so-called intermediate skin or barrier between the actual liquid container and the ships hull. To this end, one or more inner vessels may be received in the intermediate receptacle which is supported on and affixed to the hull wall by load-supporting insulation while a layer of relatively elastic or yieldable nonload-supporting thermal insulation is disposed between the inner vessel and the intermediate receptacle This further insulation layer can be composed of fibrous metallurgical slags, loose, crushed mineral or packed comminuted insulation or any of the powder insulations described in Evacuated Powder Insulation for Low Temperatures, volume 1, pages 63-84 (Progress in Cryogenics). Further means is provided between the ships hull and the inner vessel and/ or between the inner vessel and the intermediate receptacle to permit expansion and contraction of the inner vessel relatively to the intermediate receptacle without stressing the mounting assemblies. One such system includes a shear rail carried by the base of the inner vessel and longitudinally shiftable against friction forces in a channel lined with a thermal insulation of load-supporting character. The insulation layer may, in turn, be received within a longitudinally extending trough formed on the hull of the ship.

The above and other objects, features and advantages of the present invention will vbecome more readily apparent from the following description, reference being made to `the accompanying drawing, in which:

FIG. 1 is a lperspective view of a corner of a receptacle in accordance with the present invention;

FIG. 2 is a vertical cross-sectional view through one of the lower edges thereof, showing how the receptacle is affixed to the ships hull and can be provided with an inner vessel;

v FIG. 3 is a detail View of the bolt assembly of low thermal conductivity;

FIG. 4 is an elevational view, greatly reduced in scale by comparison with FIGS. 1-3, showing one wall of the receptacle after thermal deformation; and

FIG. 5 is a cross-sectional detail view of the deformed wall.

Referring first to FIGS. 4 and 5, it can be seen that a principal feature of this invention resides in the discovery that walls of relatively large area can be made sufliciently flexible to permit thermal expansion and contraction withot the numerous seams hitherto required. In this case, the sheet 1 of aluminum is secured peripherally, i.e. along both sets of mutually parallel sides of the rectangular sheet 1, to a frame F, made up of four relatively thick angle-profile members 2 which have inner marginal portins 3 converging from the thickness T of the rigid profiles to the thickness t of the sheet 1. The sheet 1 is buttwelded at 1 to the marginal portions 3 of the frame members 2 which themselves are buttwelded to the transition flanges 5 of corner reinforcing cubes 4 at seams 5. The profiles 2 are here of right-angle cross-section, the flanges of which lie in the plane of the paper or extend outwardly therefrom toward the viewer. The frame F is rendered rigid by bolt assemblies 7 which are spaced therearound and by bolt assemblies 8 transfixing the corner reinforcements to the hull of the ship (cf. FIG. 3). Bolts 7 represent thermally nonconductive assemblies which position the walls of the receptacle in load-supporting beds of thermal insulation. After the receptacle has been assembled in this manner and any opening between the walls has been eliminated by appropriate welding (the bolt head being welded in a fluidtight manner to the inner surface of the wall), liquefied gas at a temperature below 160 C. is introduced into the receptacle. Instead of rupturing because of the severe thermal contraction force, the sheet 1 stretched within the frame F undergoes plastic deformation and, upon removal of the liquefied gas and warming of the vessel to ambient temperature, wrinkles, folds or corrugates as diagrammed in FIGS. 4 and 5 to provide a wall capable of compensating for thermal stress by a bellows-like movement in the plane of the wall.

Referring now to FIGS. 1-3, it can be seen that the profiles F', F and F" are joined at a corner (FIG. 1) by the reinforcing cube 4a to form a rectangular parallelepipedal configuration. In this system, the lower lefthand L-section profile F has its horizontal flange 2a welded via a beveled transition part 3a at the seam 1a to the aluminum sheet 1a while its vertical flange is welded via transition portion 3a to the vertical aluminum sheet 1b. The vertical flange of profile F is bolted via bolt assemblies represented at 7a to the vertical portion of the ships hull while the horizontal flange of profile F is bolted at assembly 7a to the floor of the inner wall of the hull by the assemblies represented at FIG. 3. The reinforcing members 4a at the corners of the receptacle have L-shaped transition flanges 5a which are welded at L- shaped seams 5a to the angular profile F" as well as L- shaped flanges 5b and 5c welded respectively along right angles to the profiles F and F which, together with profile F form the corner. The profile F" has a transition bevel 3b which is welded at seam 1a to sheet 1a and a vertical flange whose transition piece 3b" is welded to the vertical sheet 1c. Similarly, the vertical edge profile F has transition pieces 3c and 3c buttwelded to the vertical aluminum sheets 1b and 1c. At the corner of each profile F', F, and F", forming junctions with the reinforcing cube 4a, beveled edges 6 are provided. As is also apparent from FIG. 1, the corner members 4a are secured to the ships hull by sets of bolts of low thermal conductivity, represented at 8a, 8b and 8c passing through the faces 8a', 8b and 8c of the cube in three mutually perpendicular directions. The corner members 4a are thus firmly aflixed to the Ships hull to lock the frame and receptacle corner to the latter lagainst expansion and contraction.

The profile flanges 2, 2a, 2b and 2c and the corner reinforcements 4a are affixed in force-transmitting relationship to the ships hull by bolt assemblies which are represented generally at 7 in FIG. 3 and have relatively low thermal conductivities. Each assembly 7 may thus comprise a bolt 71 which passes through a slot 72 in the profile (or the corner reinforcement) to permit some expansion and contraction movement of the members (and the respective frames F etc,), while the bolt heads 73 and washers 74 overlie the slots 72. When the vessel composed of the profiles F', F", F" etc. is to be fluidtight, a weld is formed between the head 73 and the washer as represented at 75 and between the washer and the profile as represented at 76. The receptacle and frames are retained by the bolt assemblies in spaced relationship from the ships hull via pedestals formed by internally threaded metal sleeves 24 welded at 24 to the ships hull 10. Cylindrical spacers or studs 25 of fiber-reinforced synthetic resin (e.g. glass-fiber-containing phenolformaldehyde resins of low thermal conductivity, preferably resins of the Ferrocell type), are threaded into the sleeve 24 while the bolts 71 are screwed into these spacers. It has been found that there is minimal heat transfer between the ships hull 10 and the profile members via the bolt and support assemblies. Similar bolt assemblies 8 secure the cube-shaped corner members 8 to the ships hull. Between the profiles F', F, F" etc. and the inner face of the ships hull 10 a layer 11 of load-supporting thermal insulation is provided.

In FIG. 2, I show details of an assembly in which the receptacle composed of profiles F', F" and F" forms an intermediate shell or inner skin in which inner vessels V are disposed. In the gap between the walls 13 of the vessel V and the wrinkled plates 1 of the intermediate barrier, there is disposed a loose or packed insulation represented at 12, this layer of insulation being relatively yieldable or elastic to permit relative movement of the walls 1, 13 under thermal variations. While only a single vessel V is shown, it will be understood that a number of such vessels may be provided Within each receptacle, the latter forming fluid compartments of the hold of the ship preventing escaped low-temperature liquid from contacting the hull. The inner tanks or vessels V are provided with feet 14 which rest upon blocks 15 of load-supporting thermal insulation resting upon the plate 1 of the bottom frame of the intermediate receptacle. In force-transmitting relationship with this region of the plate 1, is a further block of load-supporting insulation represented at 16 and disposed between the hull 10 and the intermediate shell, thereby transferring the load of the vessel V directly to the hull. In the longitudinal vertical median plane of the vessel V and at its bottom, I provide a shear rail 23 which is frictionally retained and thermally insulated from the hull and the intermediate receptacle in accordance with the principles set forth in commonly assigned application Ser. No. 664,066, filed Aug. 29, 1967, and entitled Tankship for Liquefied Gases. Thus the shear rail 23 is a bar received in a channel-shaped layer 22 of load-supporting thermal insulation which is separated via a sheet metal partition 21, welded via aluminum profiles 32 in the bottom frame formed by profiles 1 and 2, so that the intermediate barrier extending below the vessel V is uninterrupted. The sheet aluminum partition 21 receiving the channel-shaped insulation 22 is supported by further blocks 20 and 20' of such insulation between a pair of guide rails 17 anchored via webs 18 and weldments 18 to the floor of the ship. In this manner, any leaking liquefied gas is prevented by the intermediate barrier from contacting the ships hull in spite of the fact that the inner vessels V are supported thereon and in force-transmitting relationship therewith. Relative movement between the inner vessels V and the intermediate barrier or receptacle is permitted without stress. The support structures and thermal expansion and contraction of the intermediate barrier or receptacle is allowed without stressing the pedestals or bolt assemblies 7.

The invention described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the invention.

I claim:

1. In a tankship for the transportation of liquefied gas having a hull, and a receptacle received in said hull and in load-transmitting relationship therewith, the improvement wherein said receptacle is' generally prismatic and comprises a plurality of angularly adjoining walls including at least one wall secured to said hull, said walls each being formed with a peripheral relatively rigid metallic frame, a relatively flexible sheet spanning said frame and welded peripherally thereto; mounting means for afixing said Walls in spaced relation and in forcetransmitting relationship to said hull at the respective frame; at least one liquefied gas-containing inner vessel mounted within said receptacle in spaced relationship from said walls; means affording relative movement of said inner vessel and said walls and relative movement of said inner vessel and said hull; a first layer of thermal insulation filling the space between said hull and said walls; and a second layer of thermal insulation filling the space between said vessel and said walls.

2. The improvement defined in claim 1 wherein said second layer includes an elastic layer of insulation between said inner vessel and at least one of said walls of said receptacle, said rst layer consisting of load-supporting insulation.

3. The improvement defined in claim 2, further comprising a shear rail mounted at the bottom of said inner vessel and extending longitudinally thereof, a channel formed on said hull for accommodating said rail, a channel-shaped body of load-supporting thermal insulation disposed in said channel and receiving said rail, and a sheetmetal member extending through said body and continuous with the walls of said receptacle to form a liquid-tight barrier therewith.

4. The improvement defined in claim 2 wherein said inner vessel is provided with a plurality of feet resting upon a wall of said receptacle, further comprising a first body of load-transmitting thermal insulation between each of said feet and the respective wall of said receptacle, and a second body of load-transmitting thermal insulation between the region of the wall of this receptacle beneath the respective foot and said hull.

S. The improvement defined in claim 2 wherein said receptacle further comprises generally prismatic corner reinforcements at junctions of three of said walls, and bolt means of low thermal conductivity connecting said reinforcements with said hull.

6. The improvement defined in claim 2 wherein said mounting means includes spacers between said walls and said hull and aliixed to said walls for permitting limited movement of said walls in the plane of the respective plates.

7. The improvement defined in claim 2 wherein said mounting means includes bolt assemblies having spacers composed of load-supporting thermal insulation between said walls and said hull.

8.` The improvement defined in claim 2 wherein at least some of the sheets peripherally welded to the respective frames are wrinkled to accommodate thermal expansion and contraction of the respective wall.

9. In a tankship for the transportation of liquefied gas having a hull, and a receptacle received in said hull and in load-transmitting relationship therewith, the improvement wherein said receptacle is generally prismatic and comprises a plurality of -angularly adjoining walls including at least one wall secured to said hull, said walls each being formed with a peripheral relatively rigid metallic frame, a relatively flexible sheet spanning said frame and welded peripherally thereto; mounting means for afiixing said walls in spaced relation and in force-transmitting relationship to said hull at the respective frame; at least one liquefied gas-containing inner vessel mounted within said receptacle in spaced relationship from said walls;

means affording relative movement of said innervessel and said walls and relativemovement of said inner vessel and said hull; an elastic layer of insulation between said inner vessel and at least one of said walls of said receptacle; a shear rail mounted at the bottom of'said inner vessel and extending longitudinally thereof; a channel formed on said hull for accommodating said rail; a channel-shaped body of load-supporting thermal insulation disposed in said channel and receiving said rail; and a sheetmetal member extending through said body andcontinuous with the walls of said receptacle to form a liquidtight barrier therewith.

10. The improvement defined in claim 9 wherein at least some of the sheets peripherally welded to the respective frames are wrinkled to accommodate thermal expansion and contraction of the respective wall.

11. In a tankship for the transportation of liqueed gas having a hull, and a receptacle received in said hull and in load-transmitting relationship therewith, the improvement wherein said receptacle is generally prismatic and comprises a plurality of angularly adjoining walls including at least one wall secured to said hull, said walls each being formed with a peripheral relatively rigid metallic frame, a relatively flexible sheet spanning said frameand welded peripherally thereto; mounting means for af'iixing said walls in spaced relation and in force-transmitting relationship to said hull at the respective frame; at least one liquefied gas-containing inner vessel mounted within said receptacle in spaced relationship from said walls;

means affording relative movement of said inner vessel Cil load-transmitting thermal insulation between each of said feet and the respective wall of said receptacle; and a second body of load-transmitting thermal insulation between the region of the wall of this receptacle beneath the respective foot and said hull.

12. The improvement defined in claim 11 wherein at least some of the sheets peripherally welded to the respective frames are wrinkled to accommodate thermal expansion and contraction of the respective wall.

References Cited UNITED STATES PATENTS 786,338 4/ 1905 Zimmermann 220-72 2,077,757 4/1937 Jackson 220-72 X 2,393,964 2/1946 Boardman 220-10 2,684,171 7/1954 Ernst 220-15 2,807,143 9/ 1957 Schnellhardt 220-9 3,039,418 6/1962 Versluis 220-9 X 3,064,612 11/1962 Gardner et al. 220-9 3,071,094 1/1963 Leroux 220-9 3,138,132 6/1964 Niemann 220-9 X 3,150,795 9/ 1964 Schlumberger 220-9 3,155,266 11/1964 Yamamoto 220-15 3,221,916 12/1965 Rysgaard 220-9 3,397,662 8/1968 Basile et al. 220-9 X FOREIGN PATENTS 1,201,754 9/ 1965 Germany.

JOSEPH R. LECLAIR, Primary Examiner JAMES R. GARRETT, Assistant Examiner U.S. C1. X.R. 

